The present invention relates to a lane-keep control system which controls a host vehicle so as to prevent a deviation of the host vehicle from a traveling lane.
Japanese Patent Provisional Publication No. 7-105499 discloses a lane-keep control system which starts a lane-keep control when a lane-keep control starting condition is satisfied and terminates the lane-keep control after the host vehicle is directed parallel to a traveling lane.
However, this lane-keep control system simply starts the lane-keep control according to the comparison between parameters and thresholds. Accordingly, when the lane deviation is suddenly detected in an already deviated condition of the host vehicle due to unclearness of lane markers for the traveling lane, the system starts the lane-keep control using a relatively large controlled variable. This lane-keep control using the large controlled variable at a deviated area applies a strange feeling to a driver.
It is therefore an object of the present invention to provide an improved lane-keep control system which executes a lane-keep control according to a deviation state of the host vehicle so as not to apply a strange feeling to a driver.
An aspect of the present invention resides in a lane-keep control system which is for a host vehicle and comprises a control unit. The control unit is configured to detect a traveling condition of the host vehicle, to determine whether there is a tendency of a lane deviation indicative that the host vehicle is deviating from a traveling lane, according to the traveling condition, to execute a lane-keep control for controlling the host vehicle toward a deviation-preventing direction of preventing the lane deviation according to the traveling condition when there is the tendency of the lane deviation, and to limit the lane-keep control when the lane-keep control is executed according to the determination as to the tendency of the lane deviation and when the determination as to the tendency of the lane deviation is made according to the traveling condition under a condition that the host vehicle is traveling a lane-deviation area deviated from the traveling lane.
Another aspect of the present invention resides in a method of executing a lane-keep control for controlling a host vehicle toward a deviation-preventing direction of preventing a lane deviation. The method comprises an operation for detecting a traveling condition of the host vehicle; an operation for determining whether there is a tendency of the lane deviation that the host vehicle is deviating from a traveling lane according to the traveling condition; an operation for executing the lane-keep control according to the traveling condition when there is the tendency of the lane deviation; and an operation for limiting the lane-keep control when the lane-keep control is executed according to the determination as to the tendency of the lane deviation and when the determination as to the tendency of the lane deviation is made according to the traveling condition under a condition that the host vehicle is traveling a lane-deviation area deviated from the traveling lane.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.